The present invention provides a projection image display device capable of both minimizing a decrease in a cooling ability and simplifying maintenance of a filter. The projection image display device according to the present invention includes a filter material for filtering external air taken into a casing, a loop-shaped filter frame onto which the filter material is mounted, a drive mechanism for rotating the filter frame in a loop direction of the loop shape, and a dust removal brush to be brought into contact with the filter material while spinning at a predetermined position. The filter material is mounted onto a part of a loop-shaped surface of the filter frame. The filter material is not mounted but a ventilation part is provided in the other part of the loop-shaped surface of the filter frame.